I stopped doing the I-vi-ii(or IV)-V pattern song medleys out of personal boredom with the repetition, but now, something as simple as key changes and variation changes have renewed my interest. Thanks for the tip UD. In addition to the songs already mentioned I throw in Oh Donna, some Platters (Twilight Time, Only You ---and Harbor Lights - although the pattern changes for Harbor Lights - but that's a good thing.
Eddie